The invention relates to a body supporting structure for a vehicle body having a passenger compartment section, a front-structure section and a rear-structure section.
The existing state of the art for manufacturing vehicle bodies has long been a unitary body shell construction, in which, by using different joining techniques, profiles, frame parts, reinforcements, sheet metal parts and skins are permanently connected with one another as steel elements and sheet metal elements and form a body-supporting structure. This category also includes the so-called monocoque construction, which is used primarily in motor sport. For example, a single-shell outer skin forms here the supporting structure of a vehicle; driver compartments are also produced using this monocoque construction as a monocoque shells and connected to the body.
A new lightweight design concept in body construction was introduced by the applicant in form of the so-called Audi Space Frame (ASF). Here, a unitary body is formed of die-cast aluminum, aluminum profiles and aluminum sheet, into which the load-bearing flat elements are integrated.
In these concepts, to optimize the crash performance, longitudinal beam structures which are connected via cross-beam support structures to provide reinforcement and support, for example, by way of cast nodes (see ASF-concept), are optimized as main load paths with regard to occurring load situations. Single load path structures are also designed to receive individual loads, such as crash loads, introduced undercarriage loads or stiffness-enhancing loads. Crash energy is dissipated by wrinkling of the employed metallic material used in these load paths.
In the context of lightweight concepts, body parts are increasingly constructed as hybrid components from a combination of metal and fiber-reinforced plastic (FRP) or as a plastic component made of a FRP material.
For example, a body-supporting structure is known from EP 1 781 527 B1 which has a modular structure constructed as a central body section with the passenger compartment and a front body section. The central body section is produced as a support frame from aluminum profiles and connected to a base plate. Both the base plate and the front body section are made from a fiber composite material, such as carbon fibers, Kevlar fibers and/or glass fibers. According to EP 1 781 527 B1 it is also proposed to likewise produce the central body partially or completely from a fiber composite material.
DE 10 2010 014 574 A1 discloses a vehicle body of modular construction, which also consists of a unitary passenger compartment and a front- and rear-structure section attached thereto, wherein the passenger compartment includes a trough-shaped bottom section made of fiber-reinforced plastic with a front wall and a rear wall. The front-structure section and the rear-structure section are attached to this front wall and rear wall with screws.
Although energy absorbing elements made of a fiber composite material have a higher specific energy absorption capability than metallic longitudinal or transverse beams, such structures made of fiber-reinforced plastic exhibit an unfavorable crash behavior, since these structures dissipate crash energy in a progressive compression process (crushing) which causes their complete destruction, so that the residual strength is not sufficient to hold the attached structural elements together.
It is also known to take nature as a model for lightweight structures and to replicate nature as a bionic design, which is intended for maximum weight savings while providing optimal stability.
Such a concept was pursued by Daimler AG in the development of a concept vehicle, referred to as “Bionic Car”. This vehicle was constructed with an optimized basic structure inside an optimal aerodynamic shell, with a boxfish used as a fluid dynamics model. This optimized basic structure was developed by using software simulating a bone mineralization process, which produces load-oriented structural proposals for technical components. However, this Bionic Car concept was not produced in series.
Furthermore, it is also known to develop vehicle body parts with an optimal bionic design, as described for example in DE 10 2009 052 920 A1 in relation to a subcarrier to be attached to a vehicle body.